邁丹斷裂阿合奇段晚第四紀活動特征與地震危險性分析
發(fā)布時間：2018-08-28 09:52
【摘要】：邁丹斷裂是柯坪逆沖推覆構(gòu)造的根部斷裂,根據(jù)儀器記錄,它的地震活動相對較弱,因此多數(shù)學(xué)者認為該斷裂晚第四紀以來活動性不強,而野外考察發(fā)現(xiàn)阿合奇段晚第四紀以來多次活動,其活動頻率甚至超過了推覆體前鋒的逆沖斷裂,因此邁丹斷裂并不完全遵循北天山前展式構(gòu)造模式,是一條反序型活動逆沖斷裂。筆者根據(jù)前人資料并在衛(wèi)星影像遙感解譯和野外地質(zhì)調(diào)查的基礎(chǔ)上,確定了阿合奇段的幾何形態(tài)和空間展布特征。開展野外地質(zhì)調(diào)查,厘清水系、山脊、沖洪積扇的分布特點,并尋找斷裂最新活動的證據(jù),如斷層陡坎,河流階地沖洪積扇及山脊位錯等地貌現(xiàn)象。系統(tǒng)測量、對比分析斷層陡坎高度、發(fā)育程度、走向、錯斷地貌面時代。對斷裂帶的空間展布特征進行追蹤并對斷裂帶地質(zhì)地貌特征展開詳細調(diào)查,收集分析相關(guān)資料,對斷裂晚第四紀活動性做出判斷并對斷裂帶進行分段研究。選取合適位置開挖探槽、對探槽內(nèi)地震事件進行分析,采集年齡樣品并利用獲得的活動構(gòu)造定量測量參數(shù)對斷裂的危險性進行初步評估。獲得的主要結(jié)論有:(1)邁丹斷裂是柯坪逆沖推覆構(gòu)造系統(tǒng)的北邊邊界斷裂,是西南天山對沖擠壓邊界構(gòu)造變形帶與塔里木盆地的一部分。由3條斷裂彼此近于平行,總體走向北東東,傾向向北的斷裂組成,形成疊瓦狀構(gòu)造,向深部延伸,共同組成逆沖推覆構(gòu)造系統(tǒng)。邁丹斷裂形成于一個長期的遞進變形過程當(dāng)中,最新形成的F1阿合奇段具有最新的活動性。(2)邁丹斷裂可能表現(xiàn)為另外一種意義上的無序性。邁丹斷裂帶有長期的發(fā)育歷史,存在多排平行的地表斷層陡坎,斷裂數(shù)目和分支多,地震破裂的路徑具有很強的隨機性,甚至也有可能存在多條斷裂同時發(fā)生同震破裂的地震事件。(3)阿合奇段晚第四紀仍在強烈活動。阿合奇段長約60km,由2-4條產(chǎn)狀相近且大致平行的次級逆斷層組成,傾向向北,傾角相近(20-70°),組成一組鏟式逆沖斷層,并伴生有一條反傾的逆斷裂。阿合奇段的地層發(fā)育受主逆斷裂控制,下盤地層基本沒有變形,地層的變形主要發(fā)生在上盤。沿主斷裂普遍伴生反沖逆斷裂,它屬于淺部破裂,其破裂面深度有限,主斷裂和反向斷裂之間部分被擠出。從野外調(diào)查情況來看,反沖斷裂的規(guī)模遠遠小于主逆斷裂,反沖斷裂受主逆斷裂控制與主逆斷裂的同期發(fā)育,但不具備發(fā)震能力。(4)阿合奇段存在多處沖溝水系和階地邊緣被左旋錯動的痕跡。阿合奇西北洪積扇上的沖溝普遍發(fā)生左旋位錯,去除非構(gòu)造因素,左旋走滑距離普遍為陡坎高度的1.5-3倍。因階地面年齡由于測年周期原因還沒能得到,對其走滑速率還不能做出估計。(5)阿合奇段主要表現(xiàn)為山前洪積扇的斷錯變形,通過實測計算,認為其單次破裂導(dǎo)致的地表垂直錯距為2.9m,垂直滑移速率約為0.67-0.75 mm/a,由斷層活動造成的地殼水平縮短速率為1.15mm/a。玉山古溪古地震探槽揭示了其古地震離逝時間為1.76±0.22 ka。(6)地震危險性分析。首先依據(jù)地震空區(qū)理論,定性地得出了邁丹斷裂處于一個帶狀地震空區(qū)之內(nèi),根據(jù)該地震空區(qū)的表現(xiàn)形式可知,該地震空區(qū)應(yīng)屬于Mogi所定義的第二類地震空區(qū)。然后基于震級與平均同震位錯量之間的統(tǒng)計關(guān)系式最終得到阿合奇段潛在最大震級為7.5級,并利用垂直滑動速率和探槽中獲取的地震離逝時間得到阿合奇段積累的地震矩能量值,進一步得到阿合奇段潛在震級為7.4級;根據(jù)地震原地復(fù)發(fā)的時間可預(yù)報模式,利用滑動速率和同震位錯等定量參數(shù)得出地震復(fù)發(fā)間隔約為3626-3870a;最后根據(jù)建立于概率論和地震原地復(fù)發(fā)理論基礎(chǔ)上的概率評估方法最終得到未來50a、100a、200a三個時間段所積累的條件概率。
[Abstract]:Maidan fault is the root fault of the Keping thrust nappe structure. According to the instrumental records, its seismic activity is relatively weak, so most scholars think that the activity of the fault is not strong since the late Quaternary. Field investigation shows that the Aheqi section has been active many times since the late Quaternary, and its activity frequency even exceeds the thrust fault of the nappe front. Therefore, the Meidan fault does not completely follow the North Tianshan Piedmont structural model and is an anti-sequence active thrust fault. Based on the data of predecessors and on the basis of remote sensing interpretation of satellite images and field geological survey, the geometry and spatial distribution characteristics of the Aheqi section are determined. Distribution characteristics of alluvial fans and evidence of the latest activities of faults, such as fault scarps, alluvial fans on river terraces and mountain ridge dislocations, etc. Systematic measurement, comparative analysis of the height of fault scarps, development degree, strike, staggered geomorphological age. Tracking the spatial distribution characteristics of fault zones and geological and geomorphological characteristics of fault zones. Detailed investigation was carried out, relevant data were collected and analyzed, the Late Quaternary activity of the fault was judged, and the fault zone was studied in segments. The main conclusions are as follows: (1) Maidan fault is the northern boundary fault of Keping thrust nappe structure system, which is a part of the southwest Tianshan thrust compression boundary structural deformation belt and Tarim Basin. Madan fault is formed in a long-term progressive deformation process, and the newly formed F1 Aheqi section has the latest activity. (2) Madan fault may show another sense of disorder. (3) The Aheqi section is still active in the late Quaternary. The Aheqi section is about 60 km long and consists of 2-4 secondary reverse faults with similar occurrence and approximately parallel occurrence. It is inclined to the north with similar dip angle (20-70). A group of shovel thrust faults are formed and accompanied by an inverted fault. The strata of Aheqi section are controlled by the main inverted fault. The lower wall strata have no deformation basically. The deformation of strata mainly occurs in the upper wall. According to the field investigation, the scale of the thrust fault is much smaller than that of the main thrust fault. The thrust fault is controlled by the main reverse fault and develops simultaneously with the main reverse fault, but it does not have the seismogenic ability. (4) There are many left-handed dislocations of gully drainage system and terrace margin in Aheqi section. Left-lateral strike-slip distances are generally 1.5-3 times of the height of the steep ridge, and the rate of strike-slip can not be estimated because the terrace age is not yet available due to the dating period. (5) The Aheqi section is mainly characterized by the fault-slip deformation of the piedmont alluvial fan. The vertical offset of the surface caused by rupture is 2.9 m, and the vertical slip rate is about 0.67-0.75 mm/a. The horizontal crustal shortening rate caused by fault activity is 1.15 mm/a. The Guxi paleoseismic trench in Yushan reveals that the paleoearthquake departure time is 1.76.22 ka. (6) Seismic hazard analysis. Firstly, according to the theory of seismic empty area, Maidan is qualitatively obtained. The fault is located in a zonal seismic gap. According to the manifestation of the seismic gap, the seismic gap should belong to the second type of seismic gap defined by Mogi. Then, based on the statistical relationship between magnitude and mean coseismic dislocation, the potential maximum magnitude of Aheqi section is 7.5, and the vertical slip rate and exploration are used. The seismic moment energy accumulated in Aheqi section is obtained from the time of seismic departure obtained in the trough, and the potential magnitude of Aheqi section is 7.4. According to the time-predictable model of earthquake recurrence in situ, the recurrence interval is about 3626-3870a by using quantitative parameters such as slip rate and seismic dislocation. The conditional probability accumulated in the next 50, 100 and 200 years can be obtained by the probability evaluation method based on the theory of in situ earthquake recurrence.
【學(xué)位授予單位】：中國地震局蘭州地震研究所
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P315.2
本文編號：2209036
[Abstract]:Maidan fault is the root fault of the Keping thrust nappe structure. According to the instrumental records, its seismic activity is relatively weak, so most scholars think that the activity of the fault is not strong since the late Quaternary. Field investigation shows that the Aheqi section has been active many times since the late Quaternary, and its activity frequency even exceeds the thrust fault of the nappe front. Therefore, the Meidan fault does not completely follow the North Tianshan Piedmont structural model and is an anti-sequence active thrust fault. Based on the data of predecessors and on the basis of remote sensing interpretation of satellite images and field geological survey, the geometry and spatial distribution characteristics of the Aheqi section are determined. Distribution characteristics of alluvial fans and evidence of the latest activities of faults, such as fault scarps, alluvial fans on river terraces and mountain ridge dislocations, etc. Systematic measurement, comparative analysis of the height of fault scarps, development degree, strike, staggered geomorphological age. Tracking the spatial distribution characteristics of fault zones and geological and geomorphological characteristics of fault zones. Detailed investigation was carried out, relevant data were collected and analyzed, the Late Quaternary activity of the fault was judged, and the fault zone was studied in segments. The main conclusions are as follows: (1) Maidan fault is the northern boundary fault of Keping thrust nappe structure system, which is a part of the southwest Tianshan thrust compression boundary structural deformation belt and Tarim Basin. Madan fault is formed in a long-term progressive deformation process, and the newly formed F1 Aheqi section has the latest activity. (2) Madan fault may show another sense of disorder. (3) The Aheqi section is still active in the late Quaternary. The Aheqi section is about 60 km long and consists of 2-4 secondary reverse faults with similar occurrence and approximately parallel occurrence. It is inclined to the north with similar dip angle (20-70). A group of shovel thrust faults are formed and accompanied by an inverted fault. The strata of Aheqi section are controlled by the main inverted fault. The lower wall strata have no deformation basically. The deformation of strata mainly occurs in the upper wall. According to the field investigation, the scale of the thrust fault is much smaller than that of the main thrust fault. The thrust fault is controlled by the main reverse fault and develops simultaneously with the main reverse fault, but it does not have the seismogenic ability. (4) There are many left-handed dislocations of gully drainage system and terrace margin in Aheqi section. Left-lateral strike-slip distances are generally 1.5-3 times of the height of the steep ridge, and the rate of strike-slip can not be estimated because the terrace age is not yet available due to the dating period. (5) The Aheqi section is mainly characterized by the fault-slip deformation of the piedmont alluvial fan. The vertical offset of the surface caused by rupture is 2.9 m, and the vertical slip rate is about 0.67-0.75 mm/a. The horizontal crustal shortening rate caused by fault activity is 1.15 mm/a. The Guxi paleoseismic trench in Yushan reveals that the paleoearthquake departure time is 1.76.22 ka. (6) Seismic hazard analysis. Firstly, according to the theory of seismic empty area, Maidan is qualitatively obtained. The fault is located in a zonal seismic gap. According to the manifestation of the seismic gap, the seismic gap should belong to the second type of seismic gap defined by Mogi. Then, based on the statistical relationship between magnitude and mean coseismic dislocation, the potential maximum magnitude of Aheqi section is 7.5, and the vertical slip rate and exploration are used. The seismic moment energy accumulated in Aheqi section is obtained from the time of seismic departure obtained in the trough, and the potential magnitude of Aheqi section is 7.4. According to the time-predictable model of earthquake recurrence in situ, the recurrence interval is about 3626-3870a by using quantitative parameters such as slip rate and seismic dislocation. The conditional probability accumulated in the next 50, 100 and 200 years can be obtained by the probability evaluation method based on the theory of in situ earthquake recurrence.
【學(xué)位授予單位】：中國地震局蘭州地震研究所
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P315.2
【參考文獻】
相關(guān)期刊論文 前5條
1 張先康,趙金仁,張成科,任青芳,聶文英,成雙喜,潘素珍,唐周瓊;帕米爾東北側(cè)地殼結(jié)構(gòu)研究[J];地球物理學(xué)報;2002年05期
2 曲國勝,李亦綱,陳杰,寧寶坤,李巖峰,李軍,尹軍平;柯坪塔格推覆構(gòu)造幾何學(xué)、運動學(xué)及其構(gòu)造演化[J];地學(xué)前緣;2003年S1期
3 曲國勝,陳杰,陳新發(fā),Canerot J,李亦綱,尹軍平,李軍,彭琪宇,尹金輝;塔里木盆地阿圖什-八盤水磨反沖構(gòu)造系統(tǒng)研究[J];地震地質(zhì);2001年01期
4 田勤儉;丁國瑜;郝平;;南天山及塔里木北緣構(gòu)造帶西段地震構(gòu)造研究[J];地震地質(zhì);2006年02期
5 鄭民;雷剛林;黃少英;吳超;羅慎超;李曰俊;;南天山西段南緣斷裂構(gòu)造特征及對烏什凹陷發(fā)育的控制[J];地質(zhì)科學(xué);2007年04期
，本文編號：2209036
本文鏈接：http://sikaile.net/kejilunwen/diqiudizhi/2209036.html
最近更新
教材專著
